With rain falling and then the sun coming out just as the players took to the field on Saturday, a rainbow appeared over Kenilworth Road.

Luton Town’s ground may have seen better days and be in need of more than a lick of paint, but the rainbow made you think of the Wembley arch as it made its colourful appearance.

And on this showing, despite the 2-0 scoreline, Cambridge United showed they could have it in them to sustain a play-off challenge and earn another trip to the national stadium come May.

The U’s were firmly on top for the majority of the second half and did everything they could to try to force their way back into the contest after falling behind to Isaac Vassell’s 33rd-minute effort.

But they could not find a way through a stubborn Luton defence and were condemned to defeat eight minutes from time when Leon Legge was deemed to have brought down Vassell inside the box and Jordan Cook converted the penalty.

Certainly there were large parts of the first period when the Hatters played some excellent football and were much the better team, but the U’s hung in there and would have deserved an equaliser had one come along.

However, despite dominating possession after the break, chances were at a premium and the clinical finishing required was not present on this occasion.

Several intriguing battles took place on the Kenilworth Road turf, and it was certainly a real ding-dong one in the middle of the park.

James Dunne produced another of his first-class performances for the U’s, and it was definitely required due to the form of Luton’s Pelly-Ruddock Mpanzu and Luke Gambin.

Mpanzu, in a deeper lying role, and Gambin, cutting in from the right with his wand of a left foot, were on top form throughout for the Hatters and ran the show at times.

But Dunne loves a challenge and he rolled up his sleeves and got stuck in, covering huge distances, making tackles and winning plenty of second balls after the interval to help keep his team on the front foot.

Conor Newton also played a big part in proceedings as he gave the visitors plenty of energy, and he could have been the hero if he had stuck away some of the chances that fell his way.

As the U’s poured forward in the second half, so the return of right-back Brad Halliday from a knee injury came in extremely handy.

He showed off his defensive skills on more than one occasion in the first period, before virtually becoming an extra attacker in the second.

Along with Dunne, he was regularly in the right place at the right time to regain the ball and use it effectively.

“I thought Brad was incredible,” said United manager Shaun Derry. “He’s not trained for 27 days.

“We asked him to pull on the shirt on the back of only joining in a small-sided game on Friday.

“I think that just goes to show what a real accomplished right-back he is.”

Another factor in United’s good second-half display was the work put in by half-time substitute Ben Williamson.

He profited from an injury to Harrison Dunk along with Derry’s desire to match Luton’s diamond formation and go with two up front.

While Williamson and goals have not gone hand in hand this season, the striker is a valued member of the squad and his hold-up play, along with his enthusiasm to work the channels, helped the visitors build pressure.

“That was the best he’s played for us for a long time and I’m delighted for him,” said Derry.

“He’s been waiting and he’s been perhaps not on top of his game, how we would foresee a Ben Williamson performance this season.

“He can look at it in two ways – disappointed he’s started on the bench again, or optimistic he’s come off the bench and put in a really strong second-half performance.”

Sadly for the U’s it was not to be and the Hatters could have put even more gloss on the final result with a couple of late chances as gaps appeared at the back.

Substitute Lawson D’Ath shot just wide and then Will Norris, who had gone the right way when going close to keeping out Cook’s spot kick, produced a smart save from Jonathan Smith.

Derry’s men get another chance to prove their promotion credentials when they host second-placed Plymouth this Saturday.